Exploring potential of vaginal Lactobacillus isolates from South African women for enhancing treatment for bacterial vaginosis

• Published in: PLoS pathogens 2020-06, Vol.16 (6)
• Main Authors: Happel, Anna-Ursula, Kullin, Brian, Gamieldien, Hoyam, Wentzel, Nicole, Zauchenberger, Chambrez Z., Jaspan, Heather B., Dabee, Smritee, Barnabas, Shaun L., Jaumdally, Shameem Z., Dietrich, Janan, Gray, Glenda, Bekker, Linda-Gail, Froissart, Remy, Passmore, Jo-Ann S.
• Format: Article
• Language: English
• Subjects: Biology and Life Sciences; Medicine and Health Sciences; People and Places
• ISSN: 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1008559

Antibiotics continue to be the standard-of-care for bacterial vaginosis (BV), although recurrence rates are high. Vaginal probiotics may improve durability of BV treatment, although few probiotics for vaginal health contain Lactobacillus spp. that commonly colonize the lower female genital tract. Characteristics of vaginal Lactobacillus strains from South African women were evaluated for their probiotic potential in vitro compared to strains from commercial vaginal products, including growth at varying pHs, ability to lower pH, produce D-/L-lactate and H 2 O 2 , influence growth of BV-associated Gardnerella vaginalis and Prevotella bivia , adherence to cervical cells and susceptibility to antibiotics. Fifty-seven Lactobacillus strains were purified from cervico-vaginal fluid, including L . crispatus , L . jensenii , L . gasseri , L . mucosae , and L . vaginalis . L crispatus strains grew better at pHs below 4.5 and lowered pH more effectively than other strains. Production of D-/L-lactate and H 2 O 2 varied between Lactobacillus species and strains. Lactobacillus strains generally inhibited P . bivia more uniformly than G . vaginalis isolates. All vaginal Lactobacillus isolates were resistant to metronidazole while susceptibility to clindamycin varied. Furthermore, vaginal Lactobacillus strains tended to be broadly susceptible to penicillin, amoxicillin, rifampicin and rifabutin. Whole-genome-sequencing of five of the best-performing vaginal Lactobacillus strains confirmed their likely safety, due to antimicrobial resistance elements being largely absent, while putative intact prophages were present in the genomes of two of the five strains. Overall, vaginal Lactobacillus strains largely performed better in these in vitro assays than probiotic strains currently used in probiotics for vaginal health. Including the best-performing vaginal Lactobacillus isolates in a region-specific probiotic for vaginal health may result in improved BV treatment options. Lactobacillus species in the lower reproductive tract of healthy women lower vaginal pH and protect against sexually transmitted infections. However, women commonly suffer from bacterial vaginosis, a disruption in the optimal Lactobacillus -dominated genital microbiota to a more diverse one marked by higher pH, vaginal discharge and inflammation. Bacterial vaginosis is associated with adverse pregnancy outcomes and increased risk of sexually transmitted infections, including HIV. While antibiotics are the st